<!DOCTYPE html>
<html>
	<head>
		<!--
        	作者：刘开新
        	时间：2018-09-19
        	描述：作业三
        -->
		<meta charset="UTF-8">
		<title></title>
		<style>
			ul{list-style: none; }
			.tu{float: left;margin: 10px;
			background-image: url(../img/icons.png);
			width: 90px;height: 60px;
			}
   
            #tu1{
            	background-position: 0px 0px ;
            }
            #tu2{
            	background-position: 0px -170px ;
            }
            #tu3{
            	background-position: 0px -340px ;
            }
            #tu4{
            	background-position: 0 -510px ;
            }
           #tu1:hover{
            	background-position: 0px -85px ;
            }
            #tu2:hover{
            	background-position: 0px -255px ;
            }
            #tu3:hover{
            	background-position: 0px -425px ;
            }
            #tu4:hover{
            	background-position: 0 -595px ;
            }
		</style>
	</head>
	<body>
		<ul>
			<li id="tu1" class="tu"> </li>
			<li id="tu2" class="tu"> </li>
			<li id="tu3" class="tu"> </li>
			<li id="tu4" class="tu"> </li>
		</ul>		
	</body>
</html>
